doubt on Master-slave(distributed control) motion control application...

Hi,

I have a doubt on a motion control application(shoulder-elbow-wrist configured robot).
The application has 3 axis of motion each controlled by an "axis controller" hardware
with a DSP. Basically the axis controllers run a 1 ms servoloop in which it does PID
calculations. I also have a "master controller" hardware with a DSP. The master controller
sends signal over a CAN network to the axis controllers for start of motion, stopping motion,
co-ordinated motion etc. Currently I have a servoSynch cable running from "master controller" to each of "axis controllers". Basically the servosynch cable carries a 1 ms pulse train generated by the master controller. My doubt is : Is this separate cable needed to synch the axis controllers. I.e. If it is possible to program the axis controller to interrupt themselves every 1 ms, then can I get rid of this servoSynch cable and just have the communiction cables(CAN) between the master & slave? What is the common practice in such master-slave(distributed control) configurations?

regards
Viswesh

I have never worked with a system like you describe, but I do have a thought on it.

It sounds like the ServoSynch cable might be there to insure that the master and slave controllers are always in communications in "real" time. I don't think you can count on a typical network signal for this type of safety. Usually they will have some communications delay time that you gotta allow for different "packet" sizes and so on. You may need this second cable for safety alone.

Steve.